How Earth avoided a Mars-like fate and became habitable planet?

The magnetic field is vital for life on Earth’s surface as it shields the planet from the solar wind. Unfortunately, about 565 million years ago, the strength of magnetic field reduced to 10 percent of its strength today. Then, the magnetic field bounced back mysteriously, regaining its strength just before the Cambrian explosion of multicellular life on Earth.

This rejuvenation happened within a few tens of millions of years and it happened at the same time when Earth’s solid inner core formed, suggesting that the core is likely a direct cause, according to new research from scientists at the University of Rochester.

The research, published in the journal Nature Communications, provides clues about the history and future evolution of Earth and how it became a habitable planet.

"Right before the inner core started to grow, the magnetic field was at the point of collapse, but as soon as the inner core started to grow, the field was regenerated," says John Tarduno, the William R. Kenan, Jr., Professor of Geophysics in the Department of Earth and Environmental Sciences and dean of research for Arts, Sciences & Engineering at Rochester.

The researchers used paleomagnetism - studying the magnetism locked in ancient crystals - to determine two key dates in the history of the inner core, which they believe restored Earth's magnetic field.

Firstly, the solid inner core began to grow around 550 million years ago and secondly, around 450 million years ago, the growing inner core’s structure changed, marking the boundary between the innermost and outermost inner core.

How did Earth avoid a Mars-like fate?

Researchers believe that Mars once had a magnetic field, but the field dissipated, leaving it vulnerable to solar wind and the surface oceanless. It is unclear whether the absence of a magnetic field would have caused Earth to meet the same fate.

Earth certainly would've lost much more water if Earth's magnetic field had not been regenerated. The planet would be much drier and very different than the planet today," says Tarduno.

More details can be found here.